Regulatable propeller having adjustable blades



ug`5`1941 H. RElssNER vzrsu. 2,251,502

. .l REGULATABLE PROPELLER HAVING ADJUSTABLE BLADES Filed April 25, 193B '7 sheets-Sheet 1 6X4 v 3 Zz v d6 wzf 7 76 /56 .9

' C C) Q O Q @fdww- 1.\g.5, 1941. l-LRElss'NER ErAL 2,251,602

REGULATABLE PROPELLER HAVING ADJUSTABLE BLADES Filed April. 25. 193s' 'r sheets-sheet 2 f www?" wmf' Harvey-9@ Aug 5, 1941. H. RElssNl-:R Erm. 2,251,602

REGULATABLE PROPELLER HAVING ADJUSTALE BLADES Filed April 25, 195s 7 sheets-sheet s A #or-nays'.

A1195 1941- H. RElssNER fer/u. Y 2,251,602

RGULATABLE PROPELLER HAVING V.ADJ'USTABLE BLADES Filed Apr-1142.5, 133'8A u f l 7 sheets-sheet .4

Aug.5, 1941. H. RElssNER ETAL.

REGULATABLE PnoPELLER HAVING ADJUsTABLE BLADES Filed April g5. 19:58

7 Sheets-Sheet 5 Aug-5, 1941. H. Rl-:lssNER ETAL I 2,251,602

REGULATABLE PROPELLER HAvING ADJUSTABLE BLADES Filed April 25, 195s 7 sheets-sheet e Inveniors A #army Aug, 1941. l H. REISSNER UAL 2,251,602

4REGUIJATABLE PROPELLER HAVING ADJUSTABLE BLADES Filed April 25, 1938 i 7 Sheets-Sheet 7 v INVENTOR5 p Hans Rel'ssqzer MI5/red rlstlan llrrToRNEs` Parental Aeg. s, -1941 f RGULATABLE PROPELLER HAVING ADJUSTABLE BLADES Hans lleissner, Berlin-Charlottenburg, and Manfred Christian, Berlin-Dahlem, Germany Application April 25, 1938, Serial No. 204,208 In Germany August 21, 1936 8v Claims.

The present invention relates. to a variable pitch propeller and more particularly to a variable pitch propeller for aircraft of the kind in which a pair of gears is4 arranged between a mechanism supplying the power for adjusting the It 1s one object of this -invention to adapt the drivingengine to the various conditions of ight, particularly starting, climbing, fast night, diving and so forth.

It is a further object of the invention to positively adjust the governor for various predetermined speed settings.

it isa further object of the invention to prevent an undesired and excessive rotative movement of the blades, which might result in the'socalled negative thrust of the propeller when throttling the engine.

It is a further object of the invention to positively interfere with the operation of the governor to adjust the propeller blades when the engine is not Working in such manner that the same cause a minimum of air resistance and that practically no torque is exerted upon the engine.

1': is a further object to improve the operationof the pitch changing mechanism by the provision of means for supplying the power for the adjustment of the propeller blades when the engine does not drive the propeller.

A further object of the invention consists in the provision of direct mechanical means for positively establishing. certain predetermined speed vsettings of the governor.

A further object of the invention consists in the provision of means which positively shift the couplingmember into and hold it in a disconnected mid die position.

it is a further object' of the invention to modify the operation of the means for adjusting the members of the governor in such-manner lthat besides the automatic adjustment of the governora positive adjustment may be effected of the same when the driving engine is net operated.

The invention -is illustrated by way of example in the annexed drawings, of which:

Fig. 1 shows a longitudinal sectionithrough the propeller hub including the blade adjusting delli@ on line 2-2 of Fig. 2;

Fig. 2 shows a longitudinal section on line I-I of Fig. 1; f

Fig. 3 shows a cross-section on line 3-3 .of

Fig. 2;

. Fig. 4 shows an enlarged view of the stopping means for disconnecting the coupling member. and the means for holding same in a disconnected middle position;

Figs. 5 and 6 show certain operating positions of the stopping means and a control lever illustrated in Fig. 4;

Fig. 7 shows a longitudinal section through a second modification of the propeller hub. In this modication the axis of the impeller blade wheel arranged in front of the hub coincides with the axis of the reversing gear;

Fig. 8 shows an elevation partially in longitudinal section showing parts ofthe hub and the reversing gear illustrated in Fig. 7;

Fig. 9 shows on an enlargedscale a perspective view of the coupling disc between the blade roots and the blade adjusting means; and

- Fig. 10 shows vertical sections of the blade root, of said coupling discA and a Worm gear vcooper'- ating withthe propeller blade adjusting means.

blades. The front end of casing 5S is closed by` cover 5i which supports shaft 58, Figs. 1 and 2. A bevel gear 59 is keyed 'upon this shaft. The end of shaft 58 projects from the casing; it carries a cowl til on which impeller blades 6I of an impeller blade wheel are mounted; these blades are inclined towards the direction of flight. The inclination of the impeller blades 6l is preferably opposite to that of the propeller blades and chosen in such manner that when diving the impeller blade wheel does not assume an excessive speed and yet causes a speedy adjustment of the blades and furnishes suiiicient power for its adjustment.

1n the-casing portion 56 a shaft 63 is journalled iiange 62a slidably arrangedupon the shaft 63.

The flange 62a in turn bears aaginsta ball bearing 6l which is slidably arranged ina portion 62h of the hub casing. A threaded screw cap B6, is screwed into the portion B2b of the hub asing and engages with its edge the ball bearing opposite to a pairof bevel gears 66 and 66 which ll0' are provided with corresponding coupling claws and 1|. The claws 10 are provided on bevel gear 66 and the claws 1| on bevel gear 66.

Thebevel gears 66 and 66 are coaxially arranged with the shaft 63 carrying the centrifugal l5 governor; they bear by means of the ball bearings 66a and 66a against the wall 56a of the casing portion 66. The two bevel gears 66 and 69 are in constant engagement with each other by means of bevel gear 56 mounted upon shaft 20 66,` the axis -of which extends vertically to the axis o'f shaft 63 and bevel gears 66, 69.. Therefore, the two bevel gears 66, 66 can only rotate in opposite direction to each other. a

Shaft'` 63 is rotatably supported .by suitable 25 bearings; one of these bearings is the ball bearing ,61, which receives the pressure of the spring 62 and prevents twisting of the latter: a second bearing is formed as a bearing sleeve 61a mount- 4ed in a projecting portion 61h of the hub cas- 30 ing portion 66.

In conformity with the position of the coupling member 64, the cams 64a, 64b engage the corresponding claws 16 or 1| of the pair of gears The shaft 63 is accordingly rotated 35 66, 66. either the one or in the opposite sense; the r effecting this rotation is transmitted of the bevel gears of the reversing gear andthe coupling claws. 't 40 The end of the shaft 63 opposite to that carrying the centrifugalv weight 65 carries a worm 12, which drives a worm wheel 13. Two other worms not shown in e drawings are mounted upon the shaft of the worm wheel 16. These worms drive two worm wheels v14 one of which only is shown in Figs. 1-3. These worm wheels 14 -drive worms 16, on' shaft 16, which worms drive worm gears 11, Fig. 2, which are arranged coaxially with the rotating axis of the propeller. blades 16 upon a stationary plate 16 of the hub casing 56, Fig. 1; these worm gears act upon the roots of the propeller blades.

Next to worm wheels 11 facing the propeller vblades cross-disc couplings. Figs. 4 and 9.are 55 Y provided. These couplings consist of discs provided with crosswise 'arranged hatches 60h, 66e; caps 6| of the roots of the propeller blades engage by means of ribs 60a and without play from the one side grooves 66h of the discsyo from the other side worm wheel discs 11 engage by means of similar ribs 60d grooves 66e; the

transmission of vibrations of blades 16 to worm wheels 11 is hereby prevented.

The blades are rotatably supported in casin 55 66 of the propeller hub by means of ball bearings 62.v The plate 6| of the blade root, shown .at the left hand side in Fig. 2,v carries a conical `bolt 66 projecting towards the root of the op- Conlcal sleeves 66 .encase this 70 bolt 63; they are surrounded'by an annular posite blade.

member 66. By means of a threaded nut 64 screwed uponv the threaded portion of conical bolt 66 the sleeves may be pressed against the outer annular member 66 'if the conical lsleeves 75 outwardly upon the conical portion of bolt 63 and are thereby firmly pressed against annular 5 member 66.

The annular member 66 carries a stop 66 which at predetermined positionsof the propeller blades di'sengagescoupling member 64, Fig. 1, by means of a special gear shown in Figs. 1, 4-6 and described later o n.

Stop 66 may be adjusted relatively to the position of the propeller blades by turning annular member 66 upon the sleeves 66 and thereupon locking said member by means of nut 64.

At -the side of the sleeves 66 facing the nut 64 a flange is provided having a recess 66a and projecting inwardly towards the nut. 'I'his flange fltsvover a corresponding ange of the nut 64; the sleeves 66 are hereby held together with the nut 64 so as to prevent axial movement. Due to the divided construction of the two sleeves 65 the same may be placed upon the nut with their flanges interengaging before they are mounted upon the conical bolt.

Worm wheels 11 are rotatable with regard to the hub portion 16; but they are prevented from( axial displacement by means of nut 61 having a thread 61a, Fig. 2.

Shafts 15 of worms 16, Figs. 2 and 3,- may be axially shifted in sleeves 16a, Fig. 3, by means of nut 66a screwed into sleeve 16a. Sleeves 16a are located in hub membe- 66 and bear against the same by means of flange 16e. A screw bolt 66h is screwed in the nut 66a. This bolt carries a head 66e; a nut 66d acting asa counter nut holds bolt 69h in a fixed position.

The free end ofbolt 66h is rounded oil and bears against the adjacent end of shaft 16. .Shaft 16 at this end carries a many-sided head 16h by means of which it may be turned with the aid of a wrench inserted into sleeve 16a.

16d and 16e are oil channels. The oil may for instance be introduced by an opening 16f which may be closed by a threaded' plug 15g; the outer Vend of the plug is formed as a grip or handle.

'I'he channels are connected with bores 16h. and

lead to the upper surface of the shafts 16. Be-

tween the portions used for journallingjthe shafts 16 a relatively long tooth wheel 66 and spaced .therefrom a shorter tooth wheel 9| are provided.

A worm 16 is mounted upon tooth wheel 96 (Fig. 3). A worm wheel 14 is located by means of a sleeve-like projection 14a on tooth wheel '1417. A cap 14h is located in sleeve 14e the latter being located in casing portion 66 of the hub; it lmay be held in the latter against axial displacements. The portion of sleeve 14e located outside casing portion `6 6 is provided with a flange 14j by means of whichit bears against casing portion 66. Screwed into sleeve 14e is a screw bolt 1.49 the end of which projectsfrom 'the casing; this end carries a hexagon head 14h. by means of which this bolt may be adjusted.

vAt this endof the rod 93 a spring 94 is provided which acts as a storage spring; the spring sur- I rounds the rod 93 and is located between a ange 93a of the rod 93 and the front edge of the sleeve 92 facing the flange 93a. One end of the rod 93 cooperates with the shorter armvof the doublearmed lever 96 pivotally carried on bolt 95 which is mounted in the casing 55, Fig. 1. The other long arm of the double-armed lever 96 cooperates by way of a ball 96a with the one end of the shaft 63 of the centrifugal governor 65. Fixed upon shaftv63 is the coupling member 64 for the reversing gear 10a, Ha', 59, see also Fig. l.

The end of shaft 63 facing the lever 96 is provided with an annular groove 91 which in the middle position Vof the coupling 64 is entered by ball 98; which is actuated by a spring 98a and is guided in a bore 99 of bearing part 99a connected with shaft 63. This arrangement serves to prevent permanent axial reciprocating movements of the coupling member 64 due particularly to the alternating actions of the centrifugal weight 65 and the counter-spring 62. Such reciprocating movements of the coupling members 64 are not desired, las they may cause incomplete engagements of the claws to be coupled, undue wear of the latter and inaccurate operation of the stop 88.

In order to further prevent undesired reciprocating movements of the gear members 92 to 96 a special device is provided shown in Figs. 4-6.

The short arm of the lever 96 is provided with notches 00, Nose |02 of a bell-crank lever |03 which is rotatably mounted upon a pivot |02a engages these notches. The nose |02 is provided at the one arm of the bell-crank lever |03 the other arm of which bears against the sleeve 92.

The operation of the embodiment of the invention shown in Figs. 3-6 is, as follows:

Before the sto'p 88 provided at the root of the blade engages the rounded-oil end of the rod 93 the claws of the coupling member 64 are in engagement with the claws 10 of the bevel gear 68.

In this position the reducing gearing 12 to 11 is,

by means of the impeller blade cowl 60, 6|, actuated in such manner that the blade 18 is adjusted to a lower pitch and is rotated in a counterclockwise direction. l

The lever 96 and the bell-crank lever |03 hereby occupy the positions shown in Fig. the nose |02 engaging the notch |0|. The longer arm of the lever 96 is swung into a position where the claws .of the coupling member 64 engage the claws of the bevel gear 10a.

If now the adjustable stop'88 presses against the rounded-off end of the rod 93 the other end bevel gear 10a, so that the mutual engagement is interrupted. In this position the gear for adjusting the propeller blade is disconnected. Consequently, the rotation of stop 88 is inter-.- rupted and it does not exert further pressure upon rod 93 and lever 96.

When the stop 88 presses against rod 93 the latter is pushed through the sleeve -92 whereby the storage spring 94 is compressed. Simultaneously nose |02of the bell-crank lever |03 is lifted out of engagement with notch |8|, Fig. 6. When the. nose 02 is out of engagement with notch |0| spring 94 presses by means o f the displaceable sleeve 92, upon the adjacent end of the bellcrank lever |03 so that the latter is turned and nose |02 is pressed into notch |00.

Lever |03 may also perform its above described function if stop 88 is not forced to press upon rod 93. Under these conditionsrod 93 would not be displaced and the danger arises that lever 96' might come to a standstill in an undesired intermediate position.

In this case however, compression spring 9d acts as a protecting storage springand a secure position o f lever 96 is attained in spite of rod 93 not being moved by means of said spring which turns bellcrank lever |03 in a clockwise direction wherebynose |02 is pressed into notch |00, Fig. 4.

Inthis position coupling member 64 is disengaged from bevel gear 10. Simultaneously, the ball 98 engages the annular notch 91 in the shaft 63 of the governor and' holds the latter in such a position that the coupling member 64 occupies its middle position between the two bevel gears 10 and 1|.

- If now, due to the weight 65 and a faster rotation of the hub of the propeller the coupling member 64 is connected to the bevel gear 1|`a the adjusting gear 12 to 11 is driven in a sense opposite to that in which it was driven previously so that the stop 88 also is rotated in the opposite direction, i. e. in a clockwise direction wherebythe rounded-off end of the rod 93 is released. Consequently, the spring 94 is slackened or released, and the sleeve 92 may be returned; simultaneously, due to the slackof the rod presses upon the end of the control ened or released spring 94 and its reduced pressure upon sleeve 92 bell-crank lever |03 is also released so that nose |02 may leave notch |00, Fig.'6 and engage notch |0|, Fig. 5, i, e. if the lever 96, due to a preponderating centrifugal force of its longer arm, is turned in a counterclockwise direction.

By disconnecting the adjusting gear by means of stop'88 the pitch of the propeller blade maybe prevented from being reduced too much by the impellerblade cowl 6| if the driving engine is throttled for a long duration of time. Accordingly the thrust of the propeller blades is not decreased in an undesired manner during flight or even becomes negative and, if full gas is given the blades are not adjusted to -a tco low pitch, so that running-away of the` engine is prevented.

Another form of the invention is shown in Y Figs. 7 and 8. In this case the shaft 58' is carrying the impeller blade wheel 60-6I and is pro'- vided with a sleeve coupling |04 movable in the longitudinal direction of the shaft but prevented from rotating with regard thereto.A A ball bearing ||I is larranged coaxially to this coupling |04. Connected with the ball bearing 'are bolts |04a whicli'extend at an angle of 90 degrees to the shaft 58; they are engaged by a forkll0 vrigidly connected by means of an intermediate member- Illla to the supporting member ||0b ber ||a and supporting member ||0b form bellcrank lever which is pivoted about a bolt |06.V Consequently, the fork ||0 arranged at lever armA tion with the bevel gear |a or bevel gear |05b of the reversing gear. These bevel 'gears |05a, |05b are rotatably mounted upon shaft 58 but are prevented from axial movement.

The movement of the centrifugal weight |08v causes rotation of the lever arm ||0a and the of a centrifugal weight |08. Intermediate memand moves the spring ||4 out-of the position in which it cooperates with the sleeve I l2 so that the latter remains under the action of the spring 3 only. If rod ||6is moved in opposite direction so far that its collar ||1a lies flush with the outer bottom of the sleeve ||2 then the stop I5 presses against the bottom of this sleeve; thereby the latter is again actuated by' the common action of the two springs H3 and ||4.

fork ||0 connected therewith fixed thereto about the'bolt |06. The fork ||0 then displaces the bolts |04a of the coupling ember |04 or of thc ball-bearing connected hereto in such a manner that with an increased speed and outward swinging of the centrifugal weight |08the coupling member |04 is brought into engageinent with the coupling claws of the bevel gear Between the bevel gears |05a and |`05b another bevel gear |08 is rotatably located in a ball bearing |09a mounted in the casing 55. The axis of bevel gear |09 extends at an 'angle of 90 to the common axis of the other two bevel gears |05a, |0517. Bevel gear |09 ltherefore transmits movements to bevel gears |05a and |051) respectively in' such a manner that those two bevel gears |05a and |05b may rotate'inopposite directions to each other only.

A worm 12 is connected with bevel gear |05b. This-worm 12 engages'a worm wheel 13- which transmits the movements required for adjusting the blades of the propeller to such intermediate gears as are shown in Figs. 1-3. In this manner, the rotary movements are transmitted to worm wheels 14 and 15 by worms 16 and wormwheels 11, Fig. 1, upon the root of the propeller blade.

The construction shown in. Fig. 'I has the advantage that bevel gears |05a and |05b are not permanently rotated as is the case in the constructionv according to Figs. 1 and 2 but 4are rotated only if they are coupled. i

Bevel gears |05a, |0512 and |09 are located on The engagement and disengagement of the spring ||4 allows adjustment of the centrifugal governor intoA two different middle positions which correspond to two different nominal speeds f the propeller. i

Besides the collar ||1a acting upon the springs the rod I6 carries at its free end a flange ||1 which may bear against the inner bottom of the sleeve |I2. Y

The coupling member |04 may by rod H6, its ange ||1, sleeve ||2 and lever |01 as well as by the leverarm ||0a, the fork I|0 and the fork bolts |04 be so moved as4 to be positively coupled shaft 58 of the impellerwheel by means of ballbearings.

The lever arm or supporting member ||0b of the centrifugal weight |08 is rigidly connected.

to a lever arm |01 which is pivotally mounted upon bolt |06. in same manner as supporting member ||0b. The free endL of lever arm |01 has a bore in which a threaded sleeve ||2 is mounted which may be adjusted by means of a.

" theyv tend to so displace sleeve ||2 that lever arm |01 is rotated about bolt |06 in a counterclockto the bevel gear |0511. A

A spring-loaded ball |08a acting upon centrifugal weight |08 is provided at that .part of casy ing 51 in front of which weight |08 performs its rocking movements. The spring may be adjusted from the exterior by means of a screw cap |0017.- Spring-loaded ball |08a engages a recess provided in the centrifugal weight |08) so that the latter is fixed in a predetermined position (middle position) and leaves this position only if a predetermined centrifugal force is exceeded.

Rod I6 is actuated from the pilots seat by way of a leverage connected to the bolt ||8 and not shown in the drawings. Bolt ||8 is mounted on yoke |20 pivoted to bracket H9, which may be connected with the engine block'. The yoke |20 surrounds the hub of the propeller in the manner of a collar. By means of two rollers |2| yoke |20 engages a ring |22 axially shiftable upon the hub of the propeller which may assume two different axial positions. One of these positions corresponds to the disengaged middle position of the rod |23 is rod ||6 by means of an adjustable nut |23b, Fig. 8.' In'order to obtain this end the corresponding end of the rod J I6 carries a'. thread I upon which nut |23b is screwed which together wise direction. At greater speed, however, the l centrifugal weight tends to rotate lever arm |01 in a clockwise direction. A

Springs ||8 and ||4 are located parallel to the axisV of the propeller. Spring ||4 may .be engaged or disengaged by a stop H5 bearing against its end facing the sleeve I|2 anda rod ||6 acting upon stop ||5. If rod ||8 occupying the position shown in Fig. 'I is drawndownwardly a collar ||1a"provided thereon presses against stop H6 with abolt engages into a slot |23d of hub casing 55 (Fig. 8).

To compensate anunilateral pullexerted by lsprings H3, |l4 upon rod |23 a special device is arranged substantially symmetrically to the axis 6d of the hub of the propeller. This'device includes a spring |24a arranged in a cylinder |24. Spring |2411 acts upon bolt |24b one end of which bearsr by means of a stop .124e against the springend the other end of which is formed as an ear |24d through which extends the rod 4I 23. This .ear-like end of the y bolt |24b bears against a' further spring |24c also -mounted in the cylinder' |24 and bearing against the latter. By means'of ahexagonI nutl |24f screwed upon a provided .atlthe free end of bolt- |24b and resting upon', stop |24c the bolt may beadiusted with regard' to the springs. The spring |241 Aexerts a pressure upon the'ear of the bolt |2411, whereas the spring |24a exerts a pull on -the ear by way of displaceable stop |24c andv bolt `|2417.- Both i' .otally arranged upon bolt |30.

both springs II4, ||3.

Aby means of spring II3 or both springs II3, II4

springs, therefore, act upon a rod |23 in the same direction asrod IIB.

Bolt II8 is connected to the centrifugal governor by the rotatable yoke |20; roller IZI and ring |22 are displ-aceable upon the hub by means of cross rod |23 connected to'said ring and by means of control rod IIB connected to said cross rod.

As with the previously described form of lthe invention 'an adjustable stop |25 is provided at the root of the propeller blade. Stop |25 cooperates with a rod |26 displaceably mounted in sleeve |28. A storage spring |21 is provided between a flange of rod |26 and the edge of sleeve I 28 fac`- ing rod |26. 'Ihe rod, the sleeve andthe spring extend parallel to the axis of the propeller. Sleeve |28 is displaceable in casing 56 and its edge opposite the spring carries a ball |92 which cooperates with a bell-crank lever I3I, |3|a piv- The arm |3|a is connected to bolt I04a of coupling member |04 in such a manner that Awhen lever |30, |3|a is swung in a clockwise direction coupling member |04 is positively disconnected from coupling member |-b and moved into the middle position.

The portion of sleeve |28 adjacent to ball |29 carries a rounded-olf projection |32 cooperating with ball |33 located in a box I33a'of casing 55. Ball |33 bears against spring |3317.

The operation -of the form of the invention shown/in Figs. 7 and 8 is as follows:

It may be assumed that the propeller is moved by the engine at a speed corresponding to the nominal speed of the centrifugal governor. In

i this position coupling member |04 is disengaged and occupies the middle position between the two bevel gears |05 and |0517.

If now the speed of the propeller increases centrifugal weight |08 is swung outwardly against the action of spring I I3 or against the action of Centrifugal weight |08 overcoming the lessened force of centrifugal Weight |08. As has been already mentioned this causes the blades of the propeller to be adjusted to a lower pitch. Such position of the blades, however, is undesired if the motor is stopped becausev it causes a great air resistance.

Itis therefore desirable to move the blades into highest pitch, i. e. in the feathering position for the purpose of reducing the resistance to flight.

R-od I|6 serves this purpose.- If this rod is pulled downwardly, Fig. 7, it rst disconnects, by means of its collar 'II1a spring II4 from lever |01. On further return movement of rod I I6 collar II1 bears against the inner bottom of screw cap I I 2. Hereby a position of rod I I6 is obtained at which immediate disengagement of the coupling members |04 from the claws of-the coupling member |0511 may be obtained. In fact, if rod I I6 is returned still further it withdraws due to flange II1 bearing against the bottom of sleeve ||2a the latter against the action of springs II3 and I I4, whereby lever |01 is positively turned about the pivot |06 and, therefore, forked lever I I0, IIOa is rotated in the same sense, so that bolts I 04a of the coupling member acted upon bythe forked lever disconnect the coupling memberfrom bevel gear |0512.

rotates bell-crank lever H01), |I0a, in a clockgears 12 and 11 in such manner that the pitch is increased until -a predetermined speed is obtained. The above described connection to the bevel gear |05a is effected at two different speeds depending upon whether by a corresponding displacement of rod II6 spring II4 is caused to act upon lever |01 or is disconnected from the same.

If now due to the increase of the pitch the speed decreases then the pressure of spring. I I3 or of the combined springs ||3, II4 overcomes at a certain speed the centrifugal force of centrifugal Weight |08 and coupling member |04 is disconnected from the bevel gear I05a and at rst brought into the middle position.

The notch device |0811, |081) acting upon the centrifugal weight holds the coupling member in its middle position. If the speed further decreases the action of the spring exceeds -that of the centrifugal weight to such extent tha-t the locking action -of notch I08a, |081) is also overcome and ,coupling member |04 is coupled to bevel gear |0517. This bevel gear rotates in a direction opposite to that of the bevel gear I05a and therefore causes an adjustment of the propeller blades to a lower pitch. f

It is now assumed that the engine isvr to be stopped. Before this state ,is obtained coupling member |04 has been connected to bevel gear I05b On further return movement of rod ||6, coupling member |04 is moved beyond the middle position at which temporarilyl a notch, not shown in the drawings, and provided between the ring |22 and the throatof the hub becomes operative.

The coupling member |04 is hereby coupled to bevel gear |050.. Consequently, the blades of the propeller are in the above described manner adjusted to a higher pitch until the feathering position is reached.

If now the engine is to be started again and a change to normal conditions of flight is to. be effectedsprings II3 and II4 must be completely disconnected from collar I I1 and I I'Ia of rod ||6, so that the governor by means of releasing springs II3 or II3 and II4 disconnects coupling member |04 from bevel gear I05a, moves the coupling member |04 beyond the middle position and connects it to bevel gear |0511 with the result that' the blades of the propeller are again moved into a position of lower pitch. As soon as a definite position of low pitch of the blades has been reached the air current acting vupon the blades causes starting of the engine.

The operation of lrod II`6and the notches, not Y' shown inthe drawings, and provided between the ring |22 and the throat of the hub is, as follows:

After the coupling member |04 has been moved into its middle position, lone of the two notches,

' provided between ring |22 and the throat of the L If by means of springs IIS and I I4 the coupling member |04 is to be moved beyond its middle position andinto engagement with bevel gear |051) then the rod I I6 is from the pilots seat.` positively shifted upwardly whereby lfirst, due to the lifting of the collar II1 from the bottom ef the sleeve I I2, the spring- I I3 is rendered effective,

To secure this position in .which the spring I|3 alone acts the second notch is arranged between the throat of the hub and ring |22 which holds rod H in a position in which the spring ||'4 is disconnected. f

If now spring ||4 also is to be caused to act upon lever |01 and therefore upon coupling member |04 then rod ||6 after overcoming the action of the second notch isvshifted still further forwardly in the sense of the direction of flight until collar ||1a of rod H6 is lifted from stop III of spring ||4.

To allow movement of rod ||6 beyond the positions determined by the notches a ring' may be provided bythe displacement of which the notches may be rendered ineffective.

On a corresponding forward shifting of rod III springs 3 and H4 are completely rendered effective and may, at a correspondingly weak counter action of the centrifugal weight |08, connectv coupling member |04 to bevel gear |051. Hereby, the blades of the propeller are adjusted to a lower pitch.

'Io prevent undesired adjustment of the blades to a lower pitch and to avoid pitches causingl the undesired negative thrust the disconnecting device described above in connection with 'I becomes operative. Here, stop |25 arranged at the root of the blade of the propeller presses against rod |26. The latter compresses spring |21 until in opposite directionv by said impeller blade wheel, a worm gear actuating said propeller blades, va. gear train operatively inserted between said worm gear and said pair of gears, a mechanically operated coupling member for connecting said gear train with one of said pair of gears and for disconnecting the same, a speed controlled governor actuating said coupling member, mechanical means for directly controlling said governor and the ball I 33 still bearing against rounded off projection |32 of the sleeve |28 is forced away laterally from the rounded off projection. `'I'l'iereupon sleeve |28 `is quickly projected under theA axially shiftsthe coupling member in such a manner that it is disengaged from the toothed.

gear |0517. After lever I3|a and lever |3| have been moved for a certain distance thefront nose |34 of lever |3| meets a stop |34b'of the casing 56, (Fig. 7), so that the movement of the levers |3|, I3|a is stopped and, therefore, the coupling member |04 may be arrested in the disconnected middle position.

What we claim is:

1. In a variable pitch aircraft propeller a freely rotatable impeller blade wheel arranged infront of said propeller and supplying the power for the adjustment of the propeller blades, roots for said propeller blades, a pair of gears driven in opposite direction by said impeller blade wheel, a worm gear actuating said propeller blades. a gear train operatively inserted between said worm gear and said pair of gears, a mechanically operated coupling member for connecting said gear train with oneof said pair of gears and for disconnecting the same, a speed controlled governor actuating said coupling member, mechanical means -for directly controlling said governor and for positively establishing certain predetermined speed settings in accordance with the Avarious working'conditions of flight, adjustable stopping means connected for positively establishing certain predetermined speed settings in accordance with the various working conditions of night, adjustable stopping means connected with said propeller roots for disconnecting said coupling member at a predetermined position of the propeller blades and mechanical means between said adjustable stopping means and said coupling member to shift the same into and to hold Iit in its disconnected middle position, the constantly running blades of said impeller blade wheel being shaped and inclined with regard to the plane of rotation in a'manner to supply suillcient power for adjusting the propeller blades during flight when the driving engine is stopped.

3. In a variable pitch 4aircraft propeller a freely rotatable impeller blade wheel arranged infront of said propeller and supplying the power for the adjustment of the propeller blades, roots for said propeller blades, a pair of gears driven in opposite direction by said impeller blade wheel, a worm gear actuating said propeller blades, a gear train operatively inserted between said worm gear and said pair of gears, a mechanically operated coupling member for connecting said gear train with` one of said pair of gears and for disconnecting the same, a speed controlled governor actuating said coupling member, mechanical means for directly controlling said governor] and for positively establishing certain'predetermined speed settings in accordance with the vari- Y -ous working conditions of flight, said means being connected to a ring' coaxially located relative to the axis of the propeller shaft, rotating with the same and acted upon by a non-rotating member circumferentially slidable upon the hub of said propeller, adjustable stopping means connected with said rotatable propeller roots for disconnecting said coupling member at a predetermined position of the propeller blades and mechanical means between said adjustable stopping means and said coupling member to shift the same into and to hold it in its disconnected middle position.

4. In a variable pitch aircraft propeller a freely rotatable impeller bladel wheel arranged in front of said propeller and supplying the power with said propeller roots for disconnecting saidv for the adjustment-of the propeller blades, roots for said propeller blades, a pair of gears driven in opposite direction by said impeller blade wheel, a worm gear actuating said propeller blades, a gear train operatively inserted between said worm gear and said pair of gears, a mechanically operated coupling member for connecting said gear train with one of said pair of gears and for disconnecting the same. a shaft 'carrying said coupling -member and a bearing sleeve supporting said shaft, a speed controlled governor actuattermined position of the propeller blades, an anthe couplingmember in its disconnected middle position.

5. In a variable-pitch aircraft propeller a freely -rotatable impeller blade wheel arranged in front of said propeller and supplying the power for the adjustment of the propeller blades, roots for said propeller blades, a pair of gears driven in opposite direction by said impeller blade wheel, a worm gear actuating said propeller blades, a gear train operatively inserted between said `worm gear and said pair of gears, a mechanically operated coupling member for connecting said gear train with one of said pair of gears and for disconnecting the same, said coupling member and said pair of gears being located inside of the propeller hub and being constructed as a self-locking gear, a speed controlled governor actuating said coupling member, mechanical means for d irectly controlling said governor and for positively establishing certain predetermined speed. settings in accordance with the .various working conditions of flight, adustable stopping means connected with said rotatable propeller roots for disconnecting said coupling member at a predetermined position of the propeller blades and mechanical means between said adjustable stopping means and said coupling member to shift the same into and to hold it in its disconnected middle position.

6. In a variable pitch aircraft propeller a freely rotatable impeller blade wheel arranged in front of said propeller and supplying the power for the adjustment lof the propeller blades, roots for said propeller blades, a pair of gears driven in opposite direction by said impeller blade wheel, a worm gear actuating said propeller blades, a

Vgear train operatively inserted between said worm gear and said pair of gears, a mechanically operated coupling member for connecting said gear y train with one of said pair of gears and for disconnecting the same, a speed controlled governor actuating said coupling member, lmechanical means for directly controlling said governor and for positively establishing certain predetermined speed settings in accordance with the various working conditions of flight, stopping means for disconnecting said coupling member at a predetermined position of the propeller blades and limiting the change of pitch within said speed settings, mechanical means between said stopping means and said coupling member transmitting the action of said stopping means ,to said coupling member and a coupling inserted between the root of the propeller blades and the blade adjusting means, said coupling comprising a disc with crosswise located notches, said notches coactingwith ribs of said blade root and said blade adjusting means.

7. In a variable pitch aircraft propeller a freely rotatable-impeller blade wheel arranged in front of said propeller and supplying the powtrain with one ofy said pair of gears and for disconnecting the "same, a speed controlled governor actuating said coupling member, mechanical means for directly controlling said governor and for positively establishing certain predetermined speed settings in accordance with the various working conditions of the iiight, stopping means for disconnecting said coupling member at a predetermined position of thepropeller blades and limiting the change of pitch within said speed settings, mechanical means between. said stopping means and said coupling member transmitting the action of said stopping means to said coupling member and control members coacting with said stopping means, said control members comprising a control lever directly acting upon said coupling member and notches provided on .said lever, a displaceable sleeve, a rod `displ'aceable in said sleeve, said rod cooperating with said control lever and said stopping means, a spring bearing against said rod and said sleeve and a bell-crank lever having a nose and cooperating with said sleeve` and with said notches.

8; In a variable pitch aircraft propeller avfreely rotatable impeller blade wheel arranged in front of said propeller and supplying the power for the adjustment of the propeller blades, roots for said propeller blades, a pair of gears driven in opposite direction by said impeller blade wheel, a Worm gear .actuating said propeller blades, a gear train operatively inserted between said worml limiting the change of pitch within said speed settings, mechanical means between said stopping means and said coupling member to transmit. the action of the stopping means to said coupling member, said means including a shaft carrying s'aid coupling memberI said shaft being displaceable iny a bearing sleeve' against the action of' a spring, a pivotable control lever being acted upon by said shaft, said shaft having a rounded-olf end and carrying a ball engaging said control lever.

HANS REISSNER. MANFRED CHRISTIAN. 

